The contrast between parents' attitudes about vaccines today and a decade ago is striking. A survey published last week by the American Academy of Pediatrics shows that more and more moms and dads are refusing the shots for their children.

Much of the blame for this phenomenon can be attributed to continuing claims from everyone from actor Jim Carrey to Republican presidential nominee Donald Trump about the link between vaccines and autism - an idea that originated with a paper later shown to be fraudulent and that numerous scientific teams have tested exhaustively and found to be untrue.

But while many parents' scrutiny of vaccines may have been triggered by the autism theories, they have grown beyond those initial concerns.

The AAP study involves a random sampling of about 630 members in 2006 and again in 2013. They found that in 2006, 75 percent of pediatricians who responded had encountered parents who refused vaccines. By 2013, it was up to 87 percent.

That's a big change, but the more interesting part of the survey is why.

In 2006, the No. 1 reason parents were refusing vaccines was because of concerns about the ingredient thimerosal causing autism. In 2006, 74 said it was about autism. In 2013, that number had declined to 64 percent.

Nelson visited the Scripps Research Institute in Jupiter on Thursday to spotlight the research being done there to stop the mosquito-borne disease, which is suspected of causing birth defects in children.

Nelson visited the Scripps Research Institute in Jupiter on Thursday to spotlight the research being done there to stop the mosquito-borne disease, which is suspected of causing birth defects in children.

Now, more parents are refusing the vaccine on the grounds that they are "unnecessary" - 73.1 percent in 2013 vs. 63.4 percent in 2006.

That's stunning because of the scary history of infectious disease in this country. Polio once killed and paralyzed by the hundreds. An outbreak in New York City in 1916 left an estimated 27,000 people infected and 6,000 dead. The disease is now making a comeback in parts of Afghanistan and Pakistan because of poor immunization rates. In a 1964-65 rubella outbreak that is being compared to what's going on today with Zika, 1,000 babies miscarried or were aborted, and 20,000 others were born with defects because of rubella. A rubella vaccine is now one of the standard vaccines given in childhood.

The rapid speed at which a modern outbreak can spread was underscored in 2014-2015 when a single unvaccinated child with measles at Disneyland in California started an outbreak that spread to 146 people, many of whom were also unvaccinated. There were no deaths, but many became so seriously ill that they had to be hospitalized.

A lot of the recent controversy over vaccines has focused on a new vaccine for HPV, or human papillomavirus, for preteens or teenagers. The adoption of this vaccine has been low, in part because parents and pediatricians may be reluctant to discuss the fact that it protects against a sexually transmitted virus. Health officials have been focusing on the vaccine's effectiveness for preventing cancer instead.

The AAP paper's publication coincidentally came during another outbreak in the United States of an infectious disease we can prevent through immunizations. In recent months, at least 36 people have contracted mumps - whose symptoms include puffy cheeks and possibly serious respiratory symptoms - in one Long Island town.

Health officials said that some of those infected had been vaccinated, leading them to wonder whether there is a new strain going around, but that they still believe immunization provides the best precaution and urged everyone in the area who has not gotten the measles, mumps rubella (MMR) vaccine to get it right away. "We're trying to prevent this from getting larger," Lawrence Eisenstein, Nassau County's health commissioner, told ABC News.

The pediatrician survey also showed that more doctors are pushing back at parents who refuse vaccines for their children. In 2006, only 6.1 percent said they "always" dismiss patients for this. In 2014, 11.7 percent said they always dismiss patients. So if you continue to refuse vaccines, it's your right - but it may be harder to find a pediatrician willing to support that choice than before.